﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace System.Data
{
    /// <summary>
    /// IDataReaderExtension
    /// </summary>
    public  static partial class IDataReaderExtension
    {
        /// <summary>
        /// 获取列名集合
        /// </summary>
        /// <param name="this"></param>
        /// <returns></returns>
        public static IEnumerable<string> GetColumnNames(this IDataRecord @this)
        {
            return Enumerable.Range(0, @this.FieldCount).Select(@this.GetName).ToList();
        }
        /// <summary>
        /// DataReader转Entity
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="this"></param>
        /// <returns></returns>
        public static T ToEntity<T>(this IDataReader @this) where T : new()
        {
            Type type = typeof(T);
            PropertyInfo[] properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
            FieldInfo[] fields = type.GetFields(BindingFlags.Public | BindingFlags.Instance);

            var entity = new T();

            var hash = new HashSet<string>(Enumerable.Range(0, @this.FieldCount).Select(@this.GetName));

            foreach (PropertyInfo property in properties)
            {
                if (hash.Contains(property.Name))
                {
                    Type valueType = property.PropertyType;
                    property.SetValue(entity, @this[property.Name].To(valueType), null);
                }
            }

            foreach (FieldInfo field in fields)
            {
                if (hash.Contains(field.Name))
                {
                    Type valueType = field.FieldType;
                    field.SetValue(entity, @this[field.Name].To(valueType));
                }
            }

            return entity;
        }
        /// <summary>
        /// DataReader转Entities
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="this"></param>
        /// <returns></returns>
        public static IEnumerable<T> ToEntities<T>(this IDataReader @this) where T : new()
        {
            Type type = typeof(T);
            PropertyInfo[] properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
            FieldInfo[] fields = type.GetFields(BindingFlags.Public | BindingFlags.Instance);

            var list = new List<T>();

            var hash = new HashSet<string>(Enumerable.Range(0, @this.FieldCount).Select(@this.GetName));

            while (@this.Read())
            {
                var entity = new T();

                foreach (PropertyInfo property in properties)
                {
                    if (hash.Contains(property.Name))
                    {
                        Type valueType = property.PropertyType;
                        property.SetValue(entity, @this[property.Name].To(valueType), null);
                    }
                }

                foreach (FieldInfo field in fields)
                {
                    if (hash.Contains(field.Name))
                    {
                        Type valueType = field.FieldType;
                        field.SetValue(entity, @this[field.Name].To(valueType));
                    }
                }

                list.Add(entity);
            }

            return list;
        }
    }
}
